A. Field of Invention
This invention pertains to temperature compensating dual laser devices and methods for guiding vehicles to accurate pre-determined locations using converging laser beams emitting from inside a vehicle interior or an enclosed vehicle exterior location. The pre-calibrated location includes both longitudinal distance from a surface vertical line forward or rearward from the vehicle and also centering the vehicle laterally whereby the longitudinal distance accuracy is controlled by an automatic temperature compensating laser emitting device.
B. Description of the Related Art
It is well known to use a number of different devices to aid the driver of a vehicle in parking the vehicle in the correct position within a parking space, such as a garage. As vehicle sizes and garage storage of miscellaneous items such as lawn mowers, tools, bicycles, waste containers, etc. have increased, it has become increasingly difficult to properly park vehicles in the desired location. It is common for the driver of a vehicle to park their vehicle in a non-optimum position that result in the vehicle being positioned too close to the garage wall or even damaging it, parking too far away from the garage wall thus preventing the garage door from closing requiring repositioning the vehicle, or parking too far left or right laterally in the garage resulting in limited space to open the vehicle doors or causing damage to the vehicle doors when opened.
A number of devices are known to aid the driver of a vehicle in achieving the desired parking position within a garage. Various devices providing a physical object within the garage, as a target for the vehicle driver, are known. These devices include a soft ball on a string mounted to the garage ceiling, a parking stop placed on the garage floor, a flexible shaft mounted flag placed on the garage floor, and a floor mounted tire contact. Each of these devices requires contact with the vehicle and are obstacles when the vehicle is not parked in the garage. A tire contacting device is shown in U.S. Pat. 5,841, 368 to Bryant. In addition, these devices do not provide continuous guidance to the driver to achieve lateral centering within the parking space desired. A number of other devices for vehicle parking in garages include laser light devices pointing down from the ceiling of garages projecting a single laser dot, which is calibrated to impinge on a target on the hood, windshield, or dashboard of the vehicle. However, these devices require inconvenient ceiling installation and do not guide the vehicle into the proper parking position for both distance from the garage wall and lateral centering within the parking space. By the time that the laser dot is seen by the vehicle driver, insufficient distance is left to adjust the vehicle position for proper lateral centering location. As a result, the driver of the vehicle may be required to reposition their vehicle to achieve lateral centering or be content with their vehicle to be parked at an angle within the garage.
Such devices are shown in U.S. Pat. No. 6,191,706 to Kositkum, U.S. Pat. No. 6,002,346 to Bowden, U.S. Pat. No. 6,154,150 to Laubach, U.S. Pat. No. 6,531, 966 to Krieger, US Application 20020140576 by Simon and U.S. Application 20030160705 by Guetz.
U.S. Pat. No. 5,285,205 to White discloses a laser guided vehicle position system and method that utilizes a wall mounted vertically angled single laser device that projects forward to a target position on a vehicle windshield. However, such a device and method has the drawbacks of requiring a wall mounting of the laser device, placing a target on the windshield of a vehicle, and maneuvering the vehicle such that the laser beam can be seen by the vehicle driver at the entrance to a parking position, which is extremely difficult, especially in bright sunlight conditions on a transparent windshield surface.
Other devices for vehicle parking purposes include U.S Pat. No. 6,184,800 to Lewis, which uses a single laser device used in the interior of a vehicle to project an image on the garage wall that descends to a pre-determined position as the vehicle approaches the correct stopping point. However, no accurate lateral guidance can be provided by using a single laser if the vehicle approaches the garage wall at an angle. U.S Pat. No. 6,853,313 to Newcomer describes a dual laser line device that is mounted above the vehicle that emits a laser line in the center plane of the vehicle and another laser line at 90° to the center plane laser line. These two lines intersect at a target point on the vehicle when the correct vehicle position is achieved. However, the intersection of the laser line and dot do not provide continuous guidance to the vehicle operator to achieve the precise parking position desired. Also, achieving sufficient brightness of two line laser outputs for proper observation by the driver is a major issue in bright sunlight conditions. In addition, this device is significantly more complex, requires mounting on the garage ceiling, and consumes significantly more power than the present invention.
Additional devices for vehicle parking purposes include U.S. Pat. No. 5,406,395 to Wilson, et al that utilizes projected images and state of focus on a forward screen. The projected images can be holograms or images. U.S. Pat. No. 6,040,787 to Durham discloses a dual laser output device that utilizes a laser and a beam splitting device to project a dot and a line output forward of the vehicle. When the dot and line converge longitudinal distance control is achieved, but vehicle lateral positioning is not achieved.
U.S. Pat. No. 5,343,295 to Lara et al. discloses positioning of an electrically powered vehicle to an electrical charging station using two converging lasers mounted on the outside of the vehicle, in the middle of a grill, for example. The vehicle is moved towards a target on the electrical charging station and is presumably aligned properly when the two lasers intersect on the target. However, this patent does not teach that the two laser outputs must be equidistantly aligned on both sides of the target at all times as the vehicle is moved forward towards the target to achieve exact lateral centering and longitudinal distance positioning. For example, the electric vehicle using the teaching of the cited patent could approach the target at a 30 degree angle and still align both laser outputs on the target. The cited patent also does not teach that accuracy of the laser convergence point can be strongly affected by any thermal expansion or contraction of the actual device or attachment points to the vehicle used with the lasers. Thermal expansion within the device holding the two lasers, for example in hot locations, could separate the two lasers and greatly affect their point of convergence thus significantly compromising distance control to the electric docking station.
U.S. Pat. No. 6,120,052 for an optically guided trailer hitching system and U.S. Pat. No. 6,176,505 B1 for an optically guided alignment system to Capik et al. describe optical guidance systems externally mounted to a vehicle that utilize two different color optical sources that produce a third color on a target when the vehicle target location is reached. However, the current invention of this application overcomes several significant deficiencies in the Capik patents that result in a superior, easier to use method and device for accurate vehicle positioning. They are summarized as follows:                A—Slight misalignment of the two optical sources in the Capik patents can result in the two optical sources not aligning and therefore not producing a third color to indicate correct positioning has been achieved. The current invention of this application using a vertical line and two laser dots of the same color vertically aligned around it during vehicle approach and on it in the final vehicle position cannot suffer this deficiency.        B—Broad temperature ranges in use can affect longitudinal and lateral distance accuracy due to thermal expansion or contraction of the surface to which the lasers are mounted, thermal expansion or contraction of the laser holders, or thermal expansion or contraction of the particular lasers used. The current invention of this application has thermal compensation for a broad temperature use range.        C—The use of the a longitudinal target or a led sensor plate as shown in FIG. 9 of Capik patents result in an increases the cost/complexity and is not as accurate or as visually easy to use by the vehicle operator as in the current invention of this application.        D—The Capik U.S. Pat. 6,176,505 indicates that viewing the emission of the third colored light especially in sunlight can be facilitated by the use of a reflective tape or horizontal bar. Neither of these methods provide continuous maneuvering guidance or final vehicle position to the vehicle operator since, in bright sunlight, unless a shroud is used over the target, the laser beams are extremely difficult to see in sunlight. The current invention of this application provides shading over the vertical line to allow significantly improved beam visibility to the vehicle operator. It has also been discovered that the current invention also has the significant advantage by virtue of two lasers converging on a vertical line rather than on each other to use relatively inexpensive red lasers with increased power output (e.g. 5 milliwatt instead of 2.5 milliwatt) or inherent brightness by virtue of the red laser wavelength (e.g. 635 nm instead of 650 nm) to achieve significantly improved brightness in sunlight conditions and still meet the FDA requirements for Class 111a laser devices.        
The Capik patents also do not teach that laser devices mounted internally within a vehicle are not subject to the variety of conditions that can render unprotected externally mounted laser devices ineffective or undesirable such as dirty laser lens from outside dust, rain, ice, vandalism, or theft of the laser devices utilized.
U.S. patent application Publication, US 2005/0134482 by Xugang Li teaches the use of two light sources (e.g. lasers) mounted on the front most region of the vehicle that direct the light beams forward of the vehicle. In the preferred embodiment, these two light beams are both projected on a forward surface where the width between the light source dots is equivalent to the distance from the front most region of the vehicle. However, this method requires the vehicle driver to make an estimate on when the width between the dots is at the desired distance of the vehicle from the forward wall and is, therefore, not highly accurate for distance control from the forward surface. In another embodiment of the publication, a third light source is projected substantially perpendicular to the longitudinal axis of the vehicle on a side wall of the parking space for marking the vehicle's forward position. However, this method requires the vehicle driver to both look forward and sideward to verify the vehicle position and also requires a side wall to be present, which is not generally available in parking garages or parking decks.